The present relates to a revolution sensor using a magneto-electric converter element such as a Hall IC (Hall element) and a magnetic resistance element (MR element), etc..
Until now, a revolution sensor apparatus has known, such a revolution sensor apparatus comprises a magneto-electric converter element such as a Hall IC and a magnet for giving the magnetic field to the magneto-electric converter element. The magneto-electric converter element is arranged between a rotor of magnetic material (for example, a magnetic rotary body having a tooth marked projection member) which forms as a detection rotary body to be subjected to detection and the magnet. A quantitative change of the magnetic field which is caused by the revolution of the rotor of magnetic material is outputted as an electrical signal through the magneto-electric converter element and according to this electric signal the revolution speed (the revolution number) etc. is detected.
In the above stated kind of the revolution sensor apparatus, as the actual mounting embodiments for the magneto-electric converter element and the magnets etc., the various kinds of the revolution sensors have proposed, and further to obtain the good detection sensitivity the various technical proposals about the revolution sensor have devised.
For example, a revolution sensor described in Japanese utility model application laid-open No. Hei 3-48715, each of the elements such as the permanent magnets, a magneto-electric converter element and a circuit board are installed in a cylindrical form case and then these components are protected through the case. Further, between the permanent magnets and a Hall element, by intervening a magnetic pole piece having a share point at a tip end and made by a saturation magnetic flux density material, as a result the magnetic flux is concentrated to the magneto-electric converter element.
In a magnetic field detection apparatus described in Japanese patent application laid-open No. Hei-276970, a groove portion is provided to a connector in which an output pin (an electrical connective terminal) is formed by an insert molding technique, a bypass use magnet is inserted to the above stated groove portion using an adhesive agent and to protect this bypass use magnet is protected an inner case made of a non-magnetic metal is covered to a part of the connector. To a surface of the above stated inner case a mold chip where a magnetic resistance element (MR element) is molded through a resin material is fixed using an adhesive agent, and further to protect this mold chip an outer case is inserted under the pressure state to the connector.
In a moving body detection apparatus described in Japanese patent application laid-open No. Hei 6-123638, a magneto-electric converter element, a processing circuit, magnets for giving the magnetic field to the magneto-electric converter element and a yoke are installed in a cylindrical shape case and also are fixed and held by a filling-up agent where those components are filled up in this cylindrical shape case.
Further, according to the scatters in the magnetic field characteristics of the magneto-electric converter element and the magnets, to cope with a problem about a lowering of the detection sensitivity, before the fill-up of the above stated filling-up agent, the detection apparatus has a means for enable to adjust to the position in which at least one selected from the detection element, the magnets and the yoke has the maximum detection sensitivity. In concretely, by moving and adjusting the yoke on the magnets, the magnetic coupling between a Hall element being the magneto-electric converter element and the magnets is reinforced.
In a magnetic detection apparatus described in Japanese patent application laid-open No. Hei 6-186240, a magnetic resistance element (MR element) performed through a resin molding is held on a resin housing through an element holding member. This resin housing and a cylindrical shape magnet (a bias magnet) provided at a tip portion of the resin housing are covered through a non-magnetic metal cap, accordingly the magnetic resistance element (MR element) is passed through into the cylindrical shape magnet.
Further, to make carry out easily the management of an air gap which is formed between a subject (an object) to be subjected to detection (a rotor of magnetic material) and the magnetic resistance element (MR element), the element holding member for holding the magnetic resistance element (MR element) is compelled to direct for the subject to be subjected to detection. And then the above stated cap (the cap of a detective unit) receives the compelled force (under the condition opposed against the compelled force of the element holding member) and then the molding material of the magnetic resistance element (MR element) is contacted always to an inner face of the cap.
In a revolution position detection apparatus described in Japanese patent application laid-open No.
Hei 8-219709, an electrical connective terminal being a connector pin of a magneto-electric converter element is molded with an insert molding manner technique to a connector one body type resin case and magnets are inserted and fixed to this resin case. To one end of the magnet a circuit board on which the magneto-electric converter element is mounted is fixed, and further one end of the above stated electrical connective terminal is projected from the resin case. This one end of the electrical connective terminal is connected electrically to the circuit board of the magneto-electric converter element and those components (the magneto-electric converter element, the circuit board, a magnet mounting part of the resin case) are covered by a protection cap.
Further, to improve the detection sensitivity of the revolution signal, using a metal material having the strength to the revolution cap of the detection apparatus a cap thickness is made at the minimum, as a result there can afford to have a cap thickness reduction part about a gap length formed between the magnet and the rotor of magnetic material (the subject to be subjected to detection).
As sated in above, in the conventional this kind apparatus, with respect to the actual mounting embodiments (the protection embodiments) of the components such as the magneto-electric converter element, the magnet (for example, a permanent magnet), etc., the various kinds of the embodiments have proposed. Further, to improve the magnetic detection accuracy, there have been the proposals about the technique for heightening the magnetic flux density for passing through the magneto-electric converter element and about the technique for shortening the gap formed between the magnet and the rotor of magnetic material.
However, in this kind revolution sensor (the magnetic detection apparatus, the revolution position detection apparatus), the detection ability is under the control of not only the small size formation of the gap formed between the magnet and the rotor of magnetic material and further the concentration of the magnetic flux for passing through the magneto-electric converter element but also the position relationship among the three elements which are the rotor of magnetic material, the magnet and the magneto-electric converter element. However, in the above stated prior arts the latter problem about the position relationship among the three elements is not referred.